I just got back from the local friendly nj inspection station, and the guy had my car hooked up to check emissions for like 8 minutes, and said it took much longer than usual and that I'd probably fail....Well sure enough, I failed for NOx. Anyone have any ideas, judging by the numbers? 02 sensor, cat, etc? The timing was set with a light to 16 or 17 tdc before the test. I am interested in lowering the Nox, and not just to pass the test, so I would actually like to fix the problem, and not just pass the test.

91 civic hatch std d15b1

195f thermostat
water pump had a slight leak at one point
much of the radiator is blocked by coroplast
could these have an ill effect on nox?


gas standard reading

NOx 1446 2117
HC 182 46
CO 1.02 0.65
CO2 13.8
O2 0.2

Thanks Everyone!

 

From what I see...

O2 left over = weak cat or O2 sensor not working properly.
All numbers raised = weak cat or O2 sensor not working properly.
Timing... I believe spec is 16btdc you need to set to 14btdc.
You could have some carbon build-up. Try some Seafoam or some sort of de-carbonizer.

That is all. An o2 sensor and a cat should run you $120 or so. I recommend when you replace the cat replace the O2 sensor too.

 

smogman, By the name alone, I am guessing you know what you are talking about when it comes to emissions. From where would you buy the cat for a stock d15b1? Are there any good cats I could get at a retail location that will bolt up to stock exhaust? Would inexpensive, close to stock options be available at an autoparts store or just the web? Any good websites, and particular cat models?

Autozone has O.E type o2 sensors

bosch or denso? both are $45, while the universal is $20.

Thanks

frank

 

you should buy a stock o2 sensor those kragen ones suck i got and i didnt even help catco makes good stock replacement cats good luck on the smog if your an efer you know the troubles with the smog men

 

Thanks Hawk, I may try and see if I can get a catco and O.E o2 tomorrow, and see if that fixes the NOx.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by budomove &raquo;</TD></TR><TR><TD CLASS="quote">Thanks Hawk, I may try and see if I can get a catco and O.E o2 tomorrow, and see if that fixes the NOx. </TD></TR></TABLE>


you dont need a oe but yea, get a cat and test your o2 sensor

 

I just got a universal cat at a local auto parts store (Monument). It just bolted up. The last O2 I bought was a Bosch.

Haven't had any problems with either and I just passed my E-test.

If you have the know how to test the O2 sensor like was said, test it. It just takes more time to test it than replace it.

 

It sounds like you are having some cooling issues. High NO can be caused by high cylinder temps. If your car starts to heat up during the test, you will surely fail NO (speaking from past experience). I have a bad thermostat and I failed NO twice even after running seafoam through my intake manifold and replacing my PCV. Good Luck!

 

Smogman and Wakanarai, I just changed the tstat back to 170f from the 195f that was in there. I too thought it might have more to do with cooling than o2/cat, and my newish cheap autozone water pump did leak a little for a month during the summer, so maybe that is just not circulating coolant properly. I will retest on monday, and if the tstat swap didnt do it, I may just swap out the water pump, since I already have a new oem one that I bought a while back. That is someting I have wanted to fix anyway, so I'll do that, then move on to the o2 and cat if that doesnt do it. Thanks for all the advice!

frank

 

wakaranai is right. High nOX is due to high combustion temps NOT so much as the car running hotter. You may have some cooling issues but what you want to do is make it cooler in the combustion chamber area. Try going a step or two colder on your spark plug. Carbon build up may also be the culprit so you might want to clean the area too. Also retard your timing as low as possible but still within specs.

 

When the ECU see's a higher than normal temp it will try to cool it down by adding fuel. Nox is caused by high combustion temps, correct. But engine temps don't really affect it. Lean conditions, carbon/higher compression, timing, and a few other's will affect it.

Well the proof is in the pudding I say...We will see if a cooler running motor will lower Nox.

 

Ok everyone who has helped me, I think I'll seafoam it tomorrow, and check the plugs, and maybe switch to cooler ones. Then I may switch to 14btdc, but is that just for the test, or do you leave at at 14btdc afterwards? Is it good to have the car at operating temps or not? A hot cat is neccesary, but is it better to have a cooler engine? I was thinking of parking my car for an hour next door to the inspection station, and then just pulling in, and revving the engine for a few minutes to heat up the cat. Does this sound ideal?
Thanks for all the wisdom.

frank

 

The plugs are bosch platinum, what'd be a better choice?

 

We are suppose to make sure the car is at operating temp before we run it.

Watch when he does the testing and see if he uses a fan on it and also watch your temps to see if it does go up during the test. Ask him to use a fan and see if he will. I use the fan all the time.

What is your timing spec? Just go 1 degree below it.
My spec is 18btdc at 19 it had a little over 350. At 17 it dropped 250. It is not going to drop it a lot but a little here and a little there... you get what I mean.

After the test go back to spec or where you like it at.

 

Smogman, I'll ask about the fan, spec is 16 or 17btdc for me, and that is where it's set now. I think I'd rather leave the timing, and try to fix the problem. If I am 700 over the limit, and I seafoamed a can through the intake over the summer, is it probable that the seafoam would do anything? What would you see as a first measure to fix the problem if money is not an issue? I really want to fix the nox problem, not just pass the test...although I wouldnt mind passing the the test either.

frank

 

If it were me I would set the timing at 15btdc. do a de-carb, cat, and O2 sensor.

How I do the Seafoam is I run it thru the fuel pressure regulator vacuum line because it is near the middle of the manifold. I extend the hose with another so it is a foot long. Then I pour about 5oz. into a cup start the car, rev it to 2500rpms and suck the 5oz.s in and shut the car off for 10 minutes. Then I re-apply one more time.

Then run the **** out of it. One thing I would do is do the seafoam first, then put the cat and O2 sensor in. I know the bottle says it won't harm anything but that is what I would do.

 

Then that is exactly what I'll do. I may as well go thru on monday just after a seafoaming, then do the o2/cat next.
All Bow to the Smogman!

frank

 

Keep in mind that running seafoam through your IM will cause a ton of smoke to come out of your exhaust. Just hang in there and hope no one calls the fire dept.